Event driven programming
Most programmers think “Threads” when they are told to make a piece of code that should run concurrently. Also it hits them right in the face the last time they tried to make a threaded programs when they were faced by the usual problems (Races, deadlocks, etc) which are hard to detect, debug and at some time to reproduce. The behavior of threads is too unexpected as it's fully controlled by the threads scheduler not by the programmer. Another issue, the overhead of creating threads which sometimes is painful which produces an important question “What is the alternative ?” Lets think of concurrency in the following way: we will receive all the requests at the same time and queue them. Then we will assign each of them to a specific function. When this function blocks (i.e. for IO requests) or finishes we will make another one start till it blocks or finishes and so on. The question you'll have in mind “Wait a minute, that's not concurrency!!” Well, think of it this way. You ...